Blast cleaning apparatus



Feb. 9,- 1943.

R. w. Gum-ls BLAST CLEANING APPARATUS 6 Sheets- Sheet 1 lilelA March 20. 1941 Feb. 9, 1943. y R. w. GUITE 2,310,488

BLAST .CLEANING APPARATUS Filed March 2o. 1941 s Smets-sheet 4 ATTORNEY BLAST CLEANING APPARATUS Filed March. 20, 1941 Feb. 9,- 1943.

6 Sheets-Sheet 5 HIIIHH .Y zza INVENTOR 227 zzz 225 ATTORNEY Feb. 9, 1943. R, w, GUn-E l 2,310,488

BLAST CLEANING APPARATUS ATTORNEY Patented Feb. 9, i943 UNH'E BLAST CLEANING APPARATUS Roy W. Guite, Mishawaka, Ind., assigner to The American Foundry Equipment Company,

Z1 Claims.

This invention relates to blast cleaning appa.- ratus, and more particularly to a machine for blast cleaning metal castings, forgings and like articles in which the articles are successively advanced into one or more blasting zones and rotated during their residence in the blasting zones.

In accordance with this invention, a rotatably mounted frame is provided from which the articles to be cleaned are suspended from spaced hangers supported upon the frame. The frame and article supporting hangers are enclosed within a blast cabinet into Which one or more streams of abrasive are projected at blasting velocities.

An important feature of the invention isy the provision of mechanism for automatically Vrotating the supporting frame in stop-and-go stages so that the article suspended from each hanger is successively brought into the blasting zones,y there to reside for a predetermined cleaning interval before being advanced out of the blasting zones. The advancing mechanism is so constructed that the length of time during which the article resides in the blasting zone or zones can be determined and controlled so that each article will be properly and thoroughly cleaned of scale and other debris Without overblasting or damage to the articles undergoing treatment. Mechanism is further provided to automatically rotate the articles during their residence in each Y blasting zone.

The apparatus is admirably adapted for cleaning bomb and shell casings and similar articles, where it is desired to blast clean both the exterior and the interior surfaces thereof. An abrasive throwing wheel is preferably provided which is constructed and arranged to fire a fan-shaped stream of abrasive against the exterior surface of the article during residence of the article at the first blasting station and while the article is there rotated. An air blast nozzle may be positioned at the iirst blasting station to direct an abrasive blast against the interior surface of the article while the exterior surface of the article is being cleaned by the abrasive blast projected from the abrasive throwing wheel. When the exterior surface of the rotating article yat the rst blasting station has been suiiiciently cleaned and treated, the advancing mechanism automatically comes into play to rotate the supporting frameA so as to move the article at the first blasting station a predetermined distance to a second blasting station. At the second blasting station a second abrasive blast nozzle may be positioned which is so inclined as to clean the interior surfaces which Were not thoroughly cleaned a1; the first blasting station. When the second nozzle has performed its task, the advancing mechanism again comes into play to rotate the supporting frame and advance the article from the second to a third blasting station where a third blast nozzle is positioned to fire an abrasive stream against the interior surfaces of the article to clean those surfaces which have not been sufciently cleaned during residence of the article at the rst and second blasting stations. VIt will beappreciated that furtherl blast nozzles and additional abrasive throwing Wheels may be provided as may be necessary to clean all the eX- terior and interior surfaces of the particular casting, forging, or like article to be cleaned.

The blasting operations take place in one section of the cabinet only so that a substantial section of the supporting frame .is positioned outside of the blasting zones to provide a blast free zone Where the cleaned articles may be removed from the hangers and the articles to be cleaned put in place. Thus loading and unloading Yof the apparatus can continue without interruption and without danger to the workmen engage-d in loading and unloading the hangers.

For the cleaning of bomb and shell casings an improved supporting cage is provided which is constructed to receive casings of different lengths and diameters and vwhich rigidly retains the casingsin proper position for most effective blast cleaning.

The apparatus operates automatically t0 successively advance the articles into the respective blasting stations where they remain for a predetermined time interval before being automatically advanced outv of the final blasting station and to the unloading zone. The mechanism operates to almost instantly advance the articles Afrom one station to the next so that the abrasive throwing wheel or Wheels and blast nozzles maybe continuously operated Without material damage to the equipment. The advancing mechanism is positive in operation and advances the articles the correct distance so that each article is properlypositioned and centered to receive the full effect of each abrasive blast. The apparatus is sturdy and strong in construction and is highly adapted for high speed production requirements.

An object of thisA invention is to provide an improved blast cleaning apparatus wherein metal articles can be blast cleaned efciently and economically with aV minimum of attention and from which the articles may be easily and quickly removed and inserted without injury or risk to the operator.

Another object of this invention is to provide improved blast cleaning apparatus having mechanism associated therewith for automatically advancing the articles to one or more blasting stations, there to reside for a predetermined time interval before being, advanced to the next succeeding blasting station or out of the nal blasting station.

Another object of this invention is to provide blast cleaning apparatus having automatic means for advancing successive articles into and out of a series of blasting zones and rotating the articles during residence in said blasting zones.

A further object of this invention is to provide an improved blasting apparatus employing centrifugal abrasive throwing wheels and air blast nozzles so arranged and synchronized as to efficiently perform the particular blast cleaning function for which they are particularly adapted.

Other objects of this invention will become apparent as the disclosure proceeds.

Various other features and advantages of the invention will be apparent from the following particularrdescription and from an inspection of the accompanying drawings.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, a-s to its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which:

Fig. 1 is a top plan view of the blast cleaning apparatus;

Fig. 2 is a front elevational view of the apparatus;

Fig. 3 is a side elevational view of the apparatus showing certain parts broken away to illustrate certain features of construction;

Fig. 4 is an enlarged top plan view showing more particularly the mechanism for advancing and rotating the workpieces, certain parts being broken away to illustrate structural details;

Fig. 5 is an enlarged vertical cross-sectional view through the workpiece advancing and rotating mechanism as the same appears when looking in the direction ofthe arrows 5 5 of Fig. 4; and

Fig. 6 is an enlarged vertical cross-sectional view of a fragmentary portion of the work advancing and rotating mechanism.

Similar reference characters refer to similar parts throughout the several views of the drawings and specication.

Referring more particularly to the drawings, the blast cleaning apparatus generally comprises a workpiece supporting frame I supported upon a vertically extending rotatably mounted shaft or pedestal structure 2. 'I'he frame I is provided with hanger structures 3 rotatably supported around the periphery of the supporting frame This structure is contained in a suitable housing 4. Power transmission mechanism 5 suitably mounted on top of the cabinet 4 is operably connected to mechanism 6 operable to advance the workpiece supporting hangers 3 step by step into a blasting zone wherein mechanism I is provided for rotating the workpieces w carried by hangers 3 during their residence in the blasting zone.

The exterior surfaces of the workpiece w are subjected to an abrasive blast projected by an abrasive throwing wheel 8 contained within an auxiliary housing 9 positioned adjacent the workpiece containing housing 4. Abrasive throwing wheel 8 is driven by a motor I0 which may be positioned outside of the auxiliary cabinet 9. Where it is desired to clean the interior of workpieces in the form of hollow tubes or shells, the apparatus is provided with a series of air blast nozzles positioned to direct a stream of abrasive against the interior surfaces of such tubular workpieces. The air blast nozzles II are supplied with abrasive from a compressor unit 2 positioned exteriorly of the housing 4. An abrasive cycling system I3 collects the thrown abrasive from the bottom of housing 4 and supplies cleaned and screened abrasive to the abrasive throwing wheel 8 and the air blast nozzles 'I'he main housing 4 is formed of heavy plate metal supported and reinforced by framing and bracing members, and comprises a relatively straight rear wall I4 and straight side walls I5 and I6 which together form a generally rectangular enclosure housing approximately two-thirds of the workpiece supporting frame I. The front of the cabinet is enclosed by a generally arcuateshaped frontwall which presents an opening I8 through which the workpieces can be inserted and removed. Hanging rubber curtains 56 extending inwardly on each side of the door opening form a curtained vestibule I8' which protects the loading and unloading operator from richocheting abrasive. The cabinet 4 is provided with a top wall I9 which has a large circular opening I9' through which the upper portion of the workpiece supporting frame I projects. The cabinet is provided with' an inclined bottom or hopper 2U which carries the abrasive and debris into a collecting trough 20. 'I'he lower portion of the hopper may extend into a pit p provided in the iicor f upon which the cabinet rests.

The structure which supports the workpieces w and the mechanism for advancing th'e workpieces in step-by-step relation into the blast zone and rotates the workpieces in the blasting zone for a predetermined period, constitutes an important feature of this invention and will now be more particularly described.

Referring more particularly to Figs. l, 2, 4 and 5, the workpiece supporting framework comprises a horizontally disposed wheel-like frame I fixed to shaft 2, the wheel frame being formed by horizontally disposed circular plates 2|, 22 and 23 of sturdy construction, held together in unitary assembly by suitable bracing. The shaft 2 extends through aligned apertures in plates 2|, 22 and 23. Plate 2| is secured to a collar 24 which embraces the shaft 2, plate 22 is secured to a similar collar 25 which embraces the shaft 2, and plate 23 is secured to a collar 28 which also embraces the shaft 2. The lower plates 2| and 22 may be secured in fixed spaced relationship by suitable radiating gussets 27, and plates 22 and 23 may be held in fixed spaced relationship by radiating gussets 28, xed to a collar 29 which' encloses and may be riveted to the collars 25 and 26. The collars 24, 25 and 26 are so shaped that when secured to their respective frame plates 2|, 22 and 23 they may be telescoped onto the shaft 2. The frame rests upon and is secured to a supporting plate 30" which is welded to the shaft 2. A rigid framework xed to and rotating with the sh'aft 2 is thusprovided.

A plurality of hanger structures 3 are fixed in uniform spaced relationship to the periphery of the frame forming plates 2|, 2.2 and 23. Each hanger structure 3 comprises a hanger sleeve 3| which abuts against a circular metal band 33 formed of heavy metal plate xed to the periphery of the horizontal supporting plate 22. The rim plate 36 is further braced by a plurality of spaced vertical struts 32 lwelded thereto. The lower end of each strut 32 seats against an abutment ring 35 carried by the frame plate 2| so that the loaded hanger sleeves 3| will not flex or buckle the rim plate 3|). The abutment ring 35 may be welded to a ring plate 36 which in turn is welded to the underside of frame plate 2|. The rim plate 3|) may be provided with an inturned shelf portion 33 formed of heavy plate which' is suitably secured as by welding to the rim plate 3|). A circular shaped rail 39 of channel-shape crosssection is welded to the shelf plate 33 and the upper frame forming plate 23. The circular rail member 39 may be of somewhat less diameter than the rim plate 3l! so that a circular rail member 34 of angle-shaped cross-section may be seated upon and secured to the outer periphery of the shelf plate 33. The rim plate 33, the struts 32 and the circular rail member 39 serve to integrally secure the peripheries of the horizontal frame forming plates 2|, 22 and 23 in a rigid structural assembly so that the framework thus formed will carry great weight without weaving or buckling during rotation. The top frame plate 23 may be greater in diameter than the intermediate frame plate 22 so that the peripheral edge 23' thereof extends beyond the opening I9 in the top wall I9 of the cabinet to block the upward movement of abrasive. Suitable apertures 3'! are provided in the frame plate 23 through which the hanger sleeves 3| extend. Similarly the lower frame plate 2| may be of increased diameter to baille upwardly ilying abrasive, appropriate apertures 38 being therein provided to receive the hanger sleeves 3|.

The hanger sleeves 3 I, as shown more particularly in Figs. and 6, each comprise a tubular casing 4i] which projects a distance below the lower frame plate 2| and above the top frame plate 23. Each sleeve 43 is provided with a lower abutment portion 4| which abuts the circular rim plate 30 and an upper abutment portion 42 which abuts the upright leg of the circular rail member 34. A sturdy screw bolt extending through the vertical leg of the circular rail member 34 is threaded into a threaded aperture in the upper abutment portion 42 of the sleeve 43, thus rigidly securing the hanger sleeves 3| in position. The screw bolts 43 may be conveniently manipulated in the space between the top frame plate 23 and rail members 34 and 39.

A hanger spindle 45 is positioned to rotate in each hanger sleeve casing 4|). A circular raceway 45 ts within the upper end of the sleeve' 4I) and provides a track for ball bearings 4l. A bearing collar 48 fixed to the reduced end 49 of the spindle 45 is supported upon the bearings 41 which roll in the raceway 45, sol that the hanger spindle 45 can rotate within the sleeve 4l) with a minimum of friction. 'A sprocket wheel 5|] is fixed to the reduced end 43 of the spindle 45 and is driven by a drive chain which will hereinafter be described. A tubular sealing collar 5| is welded to the lower face of the sprocket 50 and overlaps the upper end of the tubulaihanger sleeve 40. A suitable bearing packing 52 maybe positioned within the sealing collar 5| so as to exclude grit and other foreign matter from, the spindle bearing.

The lower end of each hanger spindle 45' extends through a suitable anti-friction bearing collar 53 and suitable packing material 54 is positioned within the lower end of the sleeve 40 around the spindle 45 and retained in place by a sealing ring 55. A work supporting carrier is fixed to the lower end of each hanger spindle 45, which may vary in design depending on the shape and character of the articles to be cleaned. Where heavy bomb and shell casings are to be cleaned, the carrier '3U may be in the form of a cage comprising a top plate 6| and a bottom plate 62 connected together by a plurality of spaced vertically extending struts 83. The lower plate 62 may be provided with a central opening 54 which is surrounded by a flared collar 65 on the inside face thereof which receives the nose of the shell w and serves to align the nose end of the shell with the opening 64 in the lower cage plate. To provide for shells of different lengths, a partition plate E6 may be provided having slots 61 cut into the periphery thereof to receive the strut bars of the cage. Partition plate 65 is thus free to slide vertically in the space enclosed by the strut bars 63. The partition plate 66 is relatively heavy and is provided with a recessed lower face 5S having a surrounding collar portion 39 shaped to t around the exterior of the upper end of the shell w and retains the nose end of the shell in proper seating position within the collar 65 on lower plate 62 of the cage. When the `shell is to lbe removed the plate |56 is lifted, permitting easy withdrawal of the cleaned shell and the insertion of a shell to be cleaned. The upper plate 6! is provided with a collar 10 integrally formed therewith which receives the end of the hanger spindle 45. A key bolt extends through aligned apertures in the collar 10 and in the lower end of the spindle 45 to secure the cage thereto. It will be appreciated that cages of different sizes or other types of hangers than herein specifically shown may be used for this apparatus and can be easily attached to the end of the hanger shaft 45 by means of the key bolt '|I.

The shaft 2 which supports the framework I from which the workpieces are suspended, is heavy and sturdy in construction and is supported at its lower end by a heavy channelshaped member '|5 whose ends are secured to andsupp'orted by the main housing 4. The channel-shaped supporting member 15 supports a'thrust bearing which may comprise a sturdy bearing collar 16 secured to the flat upper side of the channel member l5. The collar member 16 contains an outer raceway ring 'il which is secured to the collar 16 and an innerraceway ring 1B fixed to the lower reduced end T9 of the shaft 2. Ball bearings 8D, positioned between the stationary bearing ring 11 and the rotating bearing ring 1B, permit substantially frictionless rotation of the shaft 2. A sealing sleeve 8| seats upon the bearing collar 16 and provides a seal for the bearing contained therein. A second sleeve 82 xed to the shaft 2 telescopes over the upstanding neck of sealing sleeve 3| so as to provide a substantially dustproof seal for the thrust bearing positioned therebelow.

The upper end of the shaft 2 is likewise journalled in a suitable anti-friction bearing which is supported upon a plate 85 welded to the lower side of a pair of parallelextending cross-beams 30 and 81 whose ends are supported by transversely extending channel-shaped sections 88 which are supported upon the top wall I9 of the housing 4. The plate 85 carries a sturdy bearing collar 90 which contains an outer raceway ring 9| fixed thereto and an inner raceway ring 32 fixed to the upper reduced end 93 of the shaft 2. Ball bearings 94 positioned between the raceway rings 9| and 92 permit the shaft 2 to rotate within the bearing collar 90 substantially without friction. A sealing plate 95 closes the upper end of the bearing collar 90 and the bearing contained therein.

Mechanism is provided for advancing the suspended cages 60 in step-by-step movement into the blasting zone of the abrasive throwing Wheel 8, in which blasting zone the cage and the Workpiece w supported therein reside for a predetermined period cluring which period it is rotated so that the outer surface of the workpiece w is blast cleaned by the thrown abrasive projected from the wheel 8. This mechanism then serves to advance this hanger and its workpiece successively into position over the respective blast nozzles II wherein the interior of the workpiece w is blast cleaned.

This mechanism is driven by motor mounted upon the top wall 9 of the housing 4, the m0- tor |00 being connected to speed reducing mechanism |0| through a drive belt |02. The driven shaft |03 of the speed reducing mechanism carries a sprocket |04 around which is trained a drive chain |05. The drive chain is also trained around a driven sprocket |06 fixed to a stub shaft |01 rotatably supported in a bearing |08 carried by the cross-beams 85 and 81. The bearing |08, as shown in Fig. 5, is secured to a movable plate I 09 that rests upon cross-beams 86 and 81, the plate |09 being adjustably secured thereto by means of bolts ||0 which extend through slots III in the plate |09. Thus by loosening the bolts I I0, the plate |09 and its bearing may be moved laterally a limited distance along the supporting beams 8B and 81 for a pur-- pose that will presently appear. The plate |09 is provided with an upstanding wall ||2 and a horizontally extending wall ||3. The underside of the horizontally extending wall ||3 carries a bearing I I4 within which the upper end of the shaft |01 is journalled.

A pair of spaced sprockets |I5 and ||6 are secured to the shaft |01 by means of suitable collars I I1 so that the sprockets II5 and- I|6 rotate with the shaft |01. A drive chain ||8 is trainedY around sprocket I|5 and a complementary drive chain I9 is trained around sprocket IIS. Drive chain II8 is also trained around a sprocket |20 and drive chain II9 is also trained around a sprocket I 2|, sprockets |20 and |2| being rotatably supported on a vertical stub shaft |22 at the other end of the cabinet. The stub shaft |22 rotates in a bearing |23 fixed to a base plate |24 supported on the top side of the frame members 86 and 81. A second base plate |25 fixed to the lower side of frame members 86 and 81 also carries a bearing |28 through which the shaft |22 extends.

As shown more particularly in Figs. 4, 5 and 6, a cam arm |30 is fixed to the lower end of the stub shaft |22. Each end of the cam arm |30 carries a downwardly projecting stud |3| which may be removably secured to the cam arm by means of a set screw |32. Each stud |3| carries a roller |33 journalled thereon by means of a Babbitt bearing |34. Each stud |3| has a head |35 which retains the roller |33 on the stud |3|.

The rollers |33 are designed to roll around the inner periphery |38 of a cam track |31 which is xed to thetop plate 23 of the framework by suitable spaced Z-shaped brackets |38. It will be noted that the cam track |31 has a circular outer periphery |39 which is of substantially the same diameter as the upper plate 23 of the frame and that its inner periphery is defined by semi-circular scalloped portions I 40 extending inwardly from the outer periphery |39. Each scalloped portion |40 may be provided with a circular opening I4I in alignment with the sprocket 50 positioned therebelow to permit ready removal of the sprocket 50 when desired. The inner periphery I 36 of each scallop I 40 provides an edge along which the rollers |33 carried by the cam arm |30 may roll, as shown more particularly in Fig. 4. Thus as the cam arm |30 fixed to shaft |22 is rotated, the rollers |33 will follow around the scalloped edge |38 of the cam track |31 so as to rotate the track |31 and the entire framework I to which it is fixed in a, generally clockwise direction as Viewed in Fig. 4.

To effect intermittent or step-by-step ridvance movement of the framework I in a clockwise direction, the shaft |22 is rotated intermittently approximately 180. The intermittent rotating movement of the shaft |22 is effected by the provision of a pawl member |45 which is fixed to the shaft |22 by means of a suitable spline |46. The pawl member |45 is positioned between the sprockets |20 and I 2| which are free to rotate on the upper end of the stub shaft I 22. The pawl member |45 is provided with a pair of diametrically opposed ears |41, as shown more particularly in Fig. 4, each ear |41 presenting an abutment surface |48. The spaced complementary chains I I8 and I I9 carry a roller |50 rotatably supported upon a vertically extending pin I5I xed to the spaced chains 8 and |I9. When the chains I8 and ||9 are driven from the shaft |01, which shaft is continuously driven by the motor |00, the roller |50 is advanced around the free riding sprockets |20 and I 2| and into contact with the abutment surface |48 of one of the ears |41 of the pawl |45. During continued travel of the roller |50 the pawl member |45 is rotated through an arc of approximately 180, causing the shaft |22 to likewise be rotated through an angle of 180. Thus the hanger spindles 45 each carrying an article supporting cage are advanced a predetermined distance which is determined by the number of scallops |40 on the cam track |31.

To maintain the drive chains ||8 and I I9 relatively tant, an angle bar |55 extending transversely between and secured to the frame members 86 and 81 is provided. The angle bar |55 carries a pair of threaded adjusting bolts |58 whose ends are adapted to abut an upturned lianger|51 provided upon the plate I 09 which supports' the chain shaft |01. By manipulating the adjusting screws |58 the shaft |01 may be moved away from the shaft |02 so as to maintain the drive chains IIB and I I9 relatively taut.

The bearing which supports the sprocket |20, as shown in Fig. 6, may comprise a bearing ring |60 xed to the interior of the sprocket |20 and a bearing ring IBI fixed to the end of the shaft I 22,. ball bearings |82 being provided therebetween. The end of shaft |22 may be capped by a primary cap I 63 which overlaps the inner bearing ring I6| and is secured to the end of the shaft by a threaded bolt |64. A secondary cap |165 extends over the shaft assembly and is secured to the sprocket |20 by bolts |66. The lower sprocket |2| may be similarly provided with an outer bearing ring |61 fixed to the interior thereof and an inner bearing ring |68 fixed to the re duced end of the stub shaft |22, roller bearings |69 being positioned between the inner and outer rings. A sealing gasket |10 positioned below the sprocket |2| is carried by a sealing plate |1| secured to the lower face of the sprocket |2| as by bolts |12. To shield the reduced end of the shaft |22 against the entry of foreign matter, circular packing rings |13 may be set into the pawl member |155 in position to ride in sealing contact with the lower surface of the sprocket |20 and the upper surface of sprocket |2|.

The bearings |23 andv |26 which support the stub shaft |22 may be similarly constructed, as shown in Fig. 6, each comprising a bearing collar |15 supported on the adjacent bed plate, The bearing collar |15 contains a bearing ring |16 forming a raceway for balls |11 which roll around a bearing sleeve or collar |18 fixed to the shaft |22. A sealing collar |19 xed to the inner bearing collar |18 rotates within a sealing gasket |80 carried in the upper edge of the bearing collar Mechanism is provided to continuously rotate the hanger spindles 05 during their residence in the blast cleaning streams. This rotating mechanism may also be driven by the motor by means of a sprocket |85 fixed to the shaft |03 of the speed reducing mechanism. A drive chain |86 is trained around the sprocket |05, the chain |86 also being trained around a sprocket |61 xed to a shaft |68. The shaft |08 is positioned exteriorly of the top wall I9 of the housing 4 and adjacent the outer periphery |39 of the cam track |31. The shaft |88 is rotatably supported in bearings |89 carried by a bracket |90 fixed to the top wall i9 of the housing 6. A sprocket |9| is fixed to the lower end of the driven shaft |86. A continuous drive chain |92 is trained around the sprocket |9| and is so arranged that the inner reach thereof will engage a predetermined `number of sprockets 56 fixed to the hanger spindles 45. The other end of the continuous drive chain |92 is trained around a sprocket |93 rotatably supported upon a stub shaft |9l'suitably xed to the top wall of the housing 9. A predetermined tensionmay be maintained upon the inner reach of the drive chain v|92 by means of an idler sprocket |95 over which the outer reach of the drive chain |92 is trained. The idler sprocket |95 rotates upon a suitable stub shaft |96 xed to a bracket |91 which may be adjustably secured to the top wall of the cabinet 4.

When the motor |00 is thrown into operation, the driven shaft |68 is rotated which advances the drive chain |92 in the direction of the arrow shown in Fig. l, which in turn rotates a predetermined number of the sprockets 50 and their associated work supports 60 so that the workpiece w is rotated within the blast stream. Ifdei vof the cabinet against the workpiece w posig tioned at the initial blasting station e. Such abrasive throwing -wheels 8 are generally well known and preferably comprise a pair of'spaoed side wall plates 200 and 20| which are arranged in xed spaced relationship by means of suitable studs or spacers. A plurality of channelshaped abrasive throwing blades 202 are radially arranged in spaced relationship between the side wall plates 200 and 20|, the inner ends of the blades extending inwardly short of the axis of rotation of the wheel to provide a central space. A normally stationary tubular control member 203 extends into the central space and is provided with a discharge outlet 204 in the tubular side wall thereof. An impeller 205 is positioned within the tubular control member 203 and is fixed to rotate with the side wall discs 200 and 20|. Abrasive is supplied to the impeller 205 by means of a suitable supply spout 206 having at its upper end an abrasive receiving funnel 201. The side wall disc 206 is fixed to a hub 208 which is secured to one end of a drive shaft .2 09 rotatably supported in spaced bearings 2|0. The bearings 2 0 are xed to a sturdy base plate2 mounted on the exterior face of the cabinet side wall I5. The wheel shaft 209 carries a sheave 2 I4 around which a V-belt drive 2 I2 is trained. The V-belt drive 2|2 is also trained around the sheave 2 |3 of the motor` l0. The motor I0 is also sturdily mounted upon the base plate 2| Abrasive throwing wheel 8 is enclosed within an auxiliary 'housing 9 comprising generally spaced front and rear walls 2|5 and 226, a side wall 2|1 and a top closing wall 2 I8. A portion of the hub 208 of the wheel extends through Va suitable opening provided inthe front wall 2 5 of the auxiliary cabinet. The side wall I5 of the m-ain cabinet may be provided with an opening which is .closed by the auxiliary cabinet 9 so that the abrasive thrown by the abrasive throwing wheel 8 is free to enter the main housing l and impinge the workpiece w positioned at blasting station a.

The compressor unit I2 is of well known construction and need not Vbe described in detail. It comprises generally a compression tank 220 which receives abrasive from the abrasive `supply pipe 22|. The 'high pressure air line 222 supplies compressed air to a mixing device 223 which also receives abrasive from the compression tank 220. The abrasive suspended in the air stream is blown through three air blast hose lines, 224, 225 and 226, each hose terminating in an air blast nozzle The vno-zzle fixed to the blast hose 224 may be positioned to .blast the interior of 'the workpiece or shell w while residing at blasting station a. This nozzle is arranged to project a stream of abrasive directly into the shell interior where the blast stream fans out and cleans the interior surface of the shell Wall as the workpiece w is rotated at that station. It will be noted that the exterior surface of the shell is cleaned at this station by abrasive projected from the abrasive throwing wheel 8. Blast hose 225 carries a rnozzle which is inclined and positioned lat blast station b. The nozzle as thus arranged will hre the abrasive against a section of the interior side wall of the shell during rotation Aof the shell at the station b. The nozzle attached to blast hose 226 is positioned at station .c and is inclined at a different angle to blast clean the uppersection of the shell interior as Ythe shellis rotated at that station.

The compression tank 220 `may be positioned exterior to but adjacent the cabinet 4 and for convenience in arrangement may be provided with a main blast line 221 which is connected directly to the mixing device 223, as shown more particularly in Fig. 1. The hose lines 224, 225 and 226 may be connected to the main blast line 221 by suitable couplings 228. The free end of the main blast line 221 is closed by means of a suitable cap plug 229. The nozzles II are adjustably supported by collars 210 adjustably secured to a suitable frame bar 21 I.

The abrasive cycling system I3 may comprise an elevator casing 230 within which is positioned a bucket elevator 23|, and comprises generally a series of abrasive receiving buckets 232 xed to a supporting belt 233. The lower end of the bucket belt 233 is trained around a lower drum 234 positioned at the bottom of the elevator casing 230, the drum 234 being fixed to a suitable shaft 235 journalled in the side walls of the elevator casing 230. The shaft 235 carries a pulley wheel 233` which is operably connected vby means of a drive belt 231 to a pulley 238 fixed to the end of a shaft 239 which is connected to a feed screw 240 positioned within the trough portion at the bottom of the hopper 20. The opposite end of the feed screw 240 may be journalled in a suitable bearing 24|.

The upper end of the bucket supporting belt 233 is trained around a drum 242 at the top of the elevator casing 230, this drum being fixed to a shaft 243 journalled in the side walls of the elevator casing 230. The projecting end of the shaft 243 carries a pulley wheel 244 opera-bly connected by the drive belt 245 to a pulley 245 fixed to a shaft 241 rotatably mounted in Ibearings 248 which are fixed to the adjacent side walls of the elevator casing 230. Shaft 241 carries a pulley wheel 249 operably connected by drive belt 250 tothe drive sheave 25| of a motor 252. 'I'he motor 252 may be suitably supported by or secured to the adjacent side wall of the elevator casing.

The abrasive and debris falling onto the hopper 20 drops into the trough 20 where it is conveyed by the conveyor screw 240 into the boot of the elevator casing 230. The elevating buckets 232 fixed to the elevator .belt 233 carry the abrasive and debris upwardly in the elevator casing 230 and discharge it into a screening and separating chamber 253 where the debris and spent abrasive is removed from the usable abrasive. The usable abrasive drops down into a hopper 254 at the lower end of the separator chamber 253. The hopper 254 terminates a discharge funnel 255 which carries a movable closure valve 256. When the closure valve 256 is open the abrasive drops down into a secondary feed funnel 251 supported upon the top wall 2|8 of the auxiliary cabinet 9 and then into the primary feed funnel 201 on the feed spout 20B. The second hopper 260 at the lower end of the separator chamber 253 leads to the abrasive supply spout 22| which supplies abrasive to the compression tank 220. The hopper legs 254 and 260 of the separator 253 also provide convenient storage hoppers for the cleaned abrasive. Dust and other air-suspended particles may be removed from the separator 253 by suitable exhaust systems connected to the dust discharge port 26|. The cabinet 4 is also provided with an exhaust port 262 through which dust laden air in the cabinet 4 may be removed.

In operating the apparatus, the elevator motor 252 is energized to drive the abrasive cycling sys- CII tem I3. The conveyor operating motor |00 is thrown into operation, the sliding doors I8 opened and the shell casing or other articles w to be cleaned are positioned within the cages 60 during residence adjacent the door opening in the front wall I1 of the cabinet. Rubber curtains 5B suspended from the front wall I1 of the cabinet may be provided to hang over the door opening to protect the workmen from abrasive that might ricochet from the cabinet interior.

The complementary drive chains II8 and II9 carrying the roller |50 therebetween continue to advance at a uniform speed when driven by the motor |00 through the speed reducing mechanism I0 I. During the advance movement of the complementary chains H0 and II9, roller |50 is advanced into abutting contact with the abutment surface |48 of the pawl |45. As the chains I|8 and II9 continue to move around the idler sprockets |20 and |2I, the pawl |45 engaged by the roller |50 is rotated through an angle of approximately Since both the pawl I 45 and the cam arm |30 are xedly secured to the shaft |22, the cam arm |30 is likewise rotated through the same 180. The rollers |33 carried by the cam arm I 30 engage the scalloped inner edge I 3B of the cam track |31 xed to the rotatable supporting frame l. One of the rollers |33 moves into the space between one pair of scalloped portions |40, and as the cam bar |30 continues to rotate the roller I 33 thus positioned exerts a driving pressure on the forward scalloped portion in the direction of the arrow shown in Fig. 4. When the supporting frame I has been rotated a distance equal to the peripheral length of one of the scalloped portions |40, the leading roller |33 is carried out of its position between that pair of scalloped portions and the roller I 33 at the other end of the cam arm is moved into the space between the next adjacent pair of scalloped portions. When this has taken place, the roller |50 carried by the drive chains I I8 and I I9 has moved out of engagement with the ear |41 of the pawl I 45 and the supporting frame comes to rest.

At this at rest position another article supporting cage 60 has been brought into loading position at the door opening in the front wall I1, and similarly article supporting cages have advanced into the respective blasting zones a, b and c. The loading operation is continued until all of the cages 60 have been loaded with articles w to be cleaned and an article w is positioned at each blasting Station a, b and c. 'Ihe wheel driving motor I0 is thrown into operation and the abrasive valve 256 swung open to supply the wheel with abrasive. 'Ihe nozzles at the respective blasting stations a, b and c are also placed in operation when the cages 60 have been loaded with the workpieces w.

It will be noted that the supporting frame I and. the workpiece supporting cages 60 remain at rest while the roller |50 xed to the complementary chains II8 and IIS has moved from the pawl |45 around the drive sprockets I|5 and IIE and back to the idler sprockets |20 and I2I into position to again engage one of the ears I 41 of the pawl |45. During this time interval the articles w are undergoing blasting treatment at blasting stations a, b and c. The time period of this blasting treatment can be controlled to ne limits by regulating the speed of the speed reducer mechanism I0| so as to vary the speed of travel of the complementary drive chains IIS and I I9.

The period of time it takes the roller I 50 to travel 180 around the idler sprockets |20 and I2I while in operative engagement with the pawl M 'ment connected to said exible Vmember adapted determines the time interval required to shift the supporting frame one stage, during which stage a partially blasted workpiece is moved into the next succeeding blasting zone, an unblasted workpiece is brought into the first blasting zone, and a fully blasted workpiece is carried out of the final blasting zone. The time required to eiect this shift is exceedingly small, making it unnecessary to cut off the abrasive supply to the blasting wheel and nozzles.

The cages 60 are easy to load inasmuch as they are brought to a full stop and so remain until the workpieces in the blasting Zones have been cleaned to the desired degree. During this interval the operator has sufficient time to remove the cleaned workpiece w from the cake -60 and replace therein an uncleaned workpiece. vLoading and unloading thus go on continuously during Operation. The apparatus operates automatically with a minimum of attention and once the speed reducing mechanism lDI Vhas been set to drive the complementary drive chains I I8 and H9 at the proper speed to insure satisfactory cleaning of the workpieces, the cleaning operation can continue without interruption.

While certain novel features of the invention have been disclosed and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

l. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive to denne a blasting Zone, a conveyor having a cam track associated therewith, means for supporting the workpiece on said conveyor, and automatic means for moving said conveyor to advance the workpiece into said blasting Zone and out of said blasting zone, said advancing means being ineffective to rotate said frame for a predetermined time interval during residence of the workpiece in said blasting Zone, said advancing means including -a driving motor, a variable speed reducer having a driving connection to said motor, an endless flexible Vmember having a driving `connection with said variable speed reducer, a rotatably mounted shaft, a pawl Xed to said shaft, an element connected to said flexible member adapted to detachably engage said pawl to rotate said shaft during only a portion of the path of travel of said iiexible member, and an 4arm fixed to `said shaft movable into and out of engagement with the cam track associated with said conveyor to advance said conveyor a predetermined distance during rotation of said shaft.

2. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive to establish a blasting Zone, a continuous conveyor, a workpiece carrier suspended from said conveyor, automatic means for moving said conveyor to advance the workpiece into said blasting Zone and out of said blasting Zone, said advancing means being ineffective to rotate said frame for a predetermined time interval during residence of the workpiece in said blasting zone, said advancing means including a continuous cam track xed to said conveyor, a driving motor, a variable speed reducer having a driving connection to said motor, lan endless flexible member having a constant driving connection with said variable speed reducer, a .rotatably vmounted shaft, la pawlxed to said'shaft,an leleto detachably engage said pawl to rotate said shaft during only a portion ofthe path of travel of said exible member, and an arm fixed to said shaft movable into and out of engagement with said continuous cam track to advance said conveyor a predetermined distance during rotation of said shaft, and means for rotating'said carrier and its workpiece during residence of the Workpiece in said stream.

3. Blast cleaning apparatus including in combination, a blasting cabinet, means for projecting a stream of abrasive to define a blasting zone in said cabinet, a rotatably mounted article supporting frame having a section thereof movable into a position adjacent said blasting Zone, means for supporting a workpiece from said frame section, and automatic means for rotating said frame to advance the workpiece into said blasting Zone and out of said blasting Zone, said advancing means being ineffective to rotate said frame for a predetermined time interval during residence of the workpiece in said blasting zone, said advancing means including a continuously driven flexible member, a rotatably mounted shaft, a pawl fixed to said shaft, an element connected to said flexible member adapted to detachably engage said pawl t-o rotate said shaft during only a portion of the path of travel of said flexible member, and an arm xed to said shaft for movement into and out of engagement with said frame to rotate said frame a predetermined distance during rotation of said shaft.

4. Blast cleaning apparatus including in combination, a cabinet, means for projecting a stream of abrasive into said cabinet to define a blasting zone therein, a supporting frame mounted for rotation in a substantially horizontal plane having a peripheral section thereof positioned adjacent said blasting zone, means for suspending a workpiece from the periphery of said frame, means for automatically rotating said frame to advance the workpiece into said blasting zone and out of said blasting zone, said advancing means being ineffective to rotate said frame vfor a predetermined time interval during residence of the workpiece in said blasting zone, said advancing means including a continuous undulating cam track fixed to said frame, a continuously driven exible member, a rotatably mounted shaft, a pawl iixed to said shaft, an element connected to said flexible member adapted to detachably engage said pawl to rotate said shaft during only a portion of the path of travel 'of said exible member, and an arm fixed to said shaft for movement into and out of engagement with said cam track to rotate said frame a predetermined Ydistance during rotation of said shaft, and means for rotating the workpiece during residence in said blasting zone.

5. Blast cleaning apparatus including in combination, a cabinet, means for projecting a stream of abrasive into said cabinet to define a blasting zone therein, a conveyor mounted for movement in a substantially horizontal plane having a section thereof positioned adjacent said blasting zone, a plurality of workpiece supporting hangers suspended from said conveyor in uniform spaced relationship, and means for automatically moving said conveyor to advance the workpieces successively into vsaid blasting zone and out of said blasting zone, said advancing means being ineffective to move said conveyor for a vpredetermined time interval during residence 'of :eachfworkpiece in sai-d blasting zone,

said advancing means including, a substantially continuous undulating cam track xed to said frame, a driving motor, a variable speed reducer having a driving connection with said motor, an endless conveyor advancing chain having a driving connection with said Variable speed reducer, a rotatably mounted shaft, a pawl fixed to said shaft, an element connected to said conveyor advancing chain adapted to detachably engage said pawl to rotate said shaft through a predetermined arc only during a portion of the path of travel of said chain, means Xed to said shaft movable into and out of engagement with said cam track to advance said conveyor a predetermined distance during rotation -of said shaft, an endless spinner chain operatively connected to said speed reducer, and sprockets associated with said hangers adapted to be moved into and out of engagement with said spinner chain to rotate said hangers and the workpieces supported thereon during residence of the workpieces in said blasting zone.

6. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive into a blasting zone, a rotatably mounted supporting frame having a peripheral section thereof positioned adjacent said blasting Zone, means for rotatably supporting a workpiece on said frame, and automatic means for rotating said frame in stop-and-go stages to carry the workpiece into the blasting zone and then out of the blasting zone after residence during a predetermined period therein, said advancing means including, a substantially endless undulating cam track fixed to said frame, a driving motor, a variable speed reducer having a driving connection with said motor, an endless frame-rotating chain having a driving connection with said variable speed reducer, a rotatably mounted shaft, a pawl fixed to said shaft, an element connected to said frame-rotating chain adapted to detachably engage said pawl to rotate said shaft through a predetermined arc only during a portion of the path of travel of said chain, means fixed to said shaft movable into and out of engagement with said cam track to rotate said frame a predetermined distance during rotation of said shaft, an endless spinner chain operatively connected to said speed reducer, and sprockets associated with said workpiece supporting means adapted to be moved into and out of engagement with said spinner chain to rotate said workpiece supporting means during residence of the workpiece in said blasting zone.

7. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive into a blasting zone, a conveyor having a section thereof positioned adjacent said blasting zone, an undulating cam track fixed to said conveyor means for supporting a workpiece from said conveyor, and automatic means for advancing said conveyor in stop-and-go stages to carry the workpiece into the blasting zone and then out of the blasting zone after residence during a predetermined time interval therein, said means including a continuously driven chain, a rotatably mounted shaft, a pawl fixed to said shaft, a stud associated with said continuously driven chain adapted to detachably engage said pawl to rotate said shaft during only a portion of the path of travel of said chain, and an arm fixed to said shaft adapted to operatively engage said cam track to advance said conveyor aI predetermined distance during rotation of said shaft.

8. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive into a blasting zone, a rotatably mounted supporting frame having a peripheral section thereof positioned adjacent said blasting zone, means for supporting a workpiece on said frame, and automatic means for rotating said frame in stop-and-go stages to carry the workpiece into the blasting zone and then out of the blasting zone after residence during a predetermined time interval therein, said means including an undulating cam track xed to said frame, a continuously driven chain, a rotatably mounted pawl, means associated with said continuously driven chain adapted to detachably engage said pawl to rotate the same during only a portion of the path of travel of said chain, and means operably con nected to said pawl and positioned to intermittently engage said cam track to rotate said frame a predetermined distance during rotation of said pawl.

9. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive into a blasting zone, a movable conveyor having a cam surface, spaced means for supporting a plurality of workpieces from said conveyor, and means operative to move said conveyor to first advance said workpieces successively into said blasting zone, then retain said workpieces successively in said blasting zone for a predetermined time interval and then advance the Workpieces successively out of the blasting zone, said means including a continuous drive chain, means for continuously driving said chain, a shaft, a pawl fixed to said shaft, an element projecting from said chain adapted to engage said pawl to rotate said shaft during only a portion of the .path of travel of said drive chain, and a cam arm fixed to said shaft operable to move into and out of engagement with said conveyor cam surface to advance said conveyor a predetermined distance during rotation of said shaft.

10. Blast cleaning apparatus including in combination, a plurality of means for projecting separate streams of abrasive into a series of spaced blasting zones, a movable conveyor, spaced means for supporting a plurality of workpieces from said conveyor, and means operative to move said conveyor to first advance said workpieces successively into said spaced blasting zones, then retain said workpieces successively in each of said blasting zones for a predetermined time interval and thence advance the workpieces successively out of the final blasting zone, said means including a continuous flexible drive member, means for continuously driving said flexible member, a shaft, a pawl fixed to said shaft, an element projecting from said flexible member adapted to engage said pawl to rotate said shaft during only a portion of the path of travel of said flexible member, a cam track fixed to said conveyor, and a cam member fixed to said shaft adapted to engage said cam track to advance said conveyor a predetermined distance while said element engages said pawl.

11. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive into a blasting zone, a rotatably mounted supporting frame having a peripheral section thereof positioned adjacent said blasting zone, means for supporting a workpiece from said frame, and means operative to first advance said workpiece into said blasting zone, then retain said workpiece in said blasting zone for a predetermined time interval and then advance the -workpiece out of said blasting zone, said means including a pair of spaced sprockets, a continuous drive chain trained around said sprockets, means for continuously driving said chain, a shaft, a pawl Xed to said shaft, an element projecting from said chain adapted to detachably engage said pawl to rotate said shaft during travel of said element around one of said sprockets, a cam track xed to said frame, and a cam arm fixed to said shaft adapted to eng-age said cam track to rotate said frame a predetermined distance while said element engages said pawl.

12. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive into a blasting zone, a rotatably mounted workpiece supporting frame having a peripheral section thereof positioned adjacent said blasting zone, and means for rotating said frame by `stop-and-go stages to rst advance said workpiece into said blasting zone, then retain said workpiece in said blasting zone for a predetermined time interval and then advance the workpiece out of said blasting zone, said means including an undulating cam track fixed to said frame, a pair of continuous complementary drive chains, a pair of sprockets at each end of said chains for supporting the same, means for driving said chains, a shaft for rotatably supporting an adjacent pair of said sprockets, a pawl xed to said shaft between said paired sprockets, an abutment element connected to said spaced chains adapted to engage said pawl to rotate said shaft through a predetermined arc during travel of said abutment element around the adjacent paired sprockets, and a cam arm associated with said shaft operably connected to engage said cam track to rotate said frame a predetermined distance during rotation of said Shaft.

13. Blast cleaning apparatus including in combination, means for projecting a stream of abrasive into a blasting zone, a rotatably mounted article supporting frame having a peripheral section thereof positioned adjacent said blasting zone, and means for rotating said frame by stopand-go stages to first advance said article into said blasting zone, then retain said article in said blasting zone for a predetermined time interval and then advance the article out of said blasting zone, said means including a pair of continuous complementary drive chains, a pair of sprockets at each end of said chains for supporting the same, means for driving said chains, a shaft for rotatably supporting an adjacent pair of said sprockets, a pawl xed to said shaft between said paired sprockets, an abutment element connected to said spaced chains adapted to engage said pawl to rotate said shaft through a predetermined arc during travel of said abutment element around the adjacent paired sprockets, a continuous cam track iiXed to said frame, and a cam arm fixed to said shaft adapted to engage said cam track and rotate said frame a predetermined distance during rotation of said shaft.

la. Blast cleaning apparatus including in cornbination, means for projecting a stream of ab-rasive into a blasting zone, a rotatably mounted article supporting frame having a peripheral section thereof positioned adjacent said blasting zone, and means for rotating said frame by stopand-go stages to first advance said article into said blasting zone, then retain said article in said blasting zone for a predetermined time interval and then advance the article out of said blasting zone, said means including a pair of continuous complementary drive chains, a pair of sprockets at each end of said chains for supporting the same, means for driving said chains, a` shaft for rotatably supporting an adjacent pair of said sprockets, a pawl fixed to said shaft between said paired sprockets, an abutment element connected to said spaced chains adapted to engage said pawl to rot-ate said shaft through a predetermined arc during travel of said abutment element around the adjacent paired sprockets, a continuous cam track xed to said frame, a cam bar xed to said shaft, and a roller rotatably secured to each end of said cam bar adapted to engage said cam track and rotate said frame a predetermined distance during rotation of said shaft.

l5. Blast cleaning apparatus including in combination, a cabinet, an abrasive throwing wheel for projecting a stream of abrasive through said cabinet at one blasting zone, air blast mechanism including a blast nozzle positioned within the cabinet Yoperable to project a stream of abrasive at a seco-nd blasting zone, a conveyor for advancing the article into said rst blasting zone posif tioned to receive the wheel blast against the exterior surface thereof during residence in said iirst blasting zone, said conveyor having mechanism associated therewith for advancing the arti.- cle from said first blasting zone to said second blasting zone wherein the interior cavities of the articles are subjected to the abrasive blast from said nozzle during residence of the article in said second blasting zone, said mechanism being further operative to advance the blasted articles Afrom said second blasting zone to an unloading zone, means including an undulating cam track nxed to said conveyor, a continuous drive chain, means for continuously driving said chain, a rotatable shaft, a pawl iixed to said' shaft, an abutment element connected to said chain and adapted to engage said paw1 to rotate said shaft through a predetermined arc during the travel of said abutment element a predetermined distance, and an arm fixed to said shaft adapted to detachably engage said cam track to advance said conveyor a. predetermined distance during rotation of said shaft.

16. Blast cleaning apparatus including in combination, a cabinet, means for projecting a stream of abrasive into said cabinet to define a blasting zo-ne therein, an article supporting frame mounted for rotation in a substantially horizontal plane having a peripheral section thereof positioned adjacent said blasting zone, means for suspending an article from the periphery of said frame, said means including a tubular sleeve xed to said frame, a spindle rotatably mounted in said sleeve, a cage fixed to the end of said spindle, a vertically movable plate carried by said cage and adapted to rest on the article to be cleaned, means for rotating said spindle, and means for automatically rotating said frame to advance the article into said blasting zone and out of said blasting zone, said advancing means being ineffective to rotate said frame for a predetermined time interval during which the article resides in said blasting zone.

17. Blast cleaning apparatus including in combination, means for projecting a stream of ab-rasive into a blasting zone, an article supporting conveyor, means for advancing said conveyor by stop-and-go stages to first advance said article into said blasting zone, then retain said article in said blasting zone for a predetermined time interval, and then advance the article out of said blasting zone, said advancing means including a cam track iixed to said conveyor, a pair of continuous complementary drive chains, apair of sprockets at each end of said chains for supporting the same, means for continuously driving said chains at variable speeds, a rotatable shaft, a -pawl fixed to said shaft, an abutment element connected to said chains and adapted to engage said pawl to rotate said shaft through a predetermined arc during the trave1 of said abutment element a predetermined distance, and an arm xed to said shaft adapted to detachably engage said cam track to advance said conveyor a predetermined distance during rotation of said shaft.

18. Blast cleaning apparatus including in combination, a cabinet, means for projecting a stream of abrasive into said cabinet to define a blasting zone therein, an article supporting conveyor, means for advancing said conveyor and the article supported thereon through said blasting zone, said conveyor having an article supporting spindle, a cage comprising a bottom plate having a seat for the article, a top plate xed to the end of said spindle, vertical bars connecting said top and bottom plates, and a vertically movable plate guided by said bars and adapted to rest on the article to be cleaned, and means for rotating said spindle and cage in said blasting zone.

19. In blast cleaning apparatus having a movable conveyor and a workpiece supporting spindle supported from said conveyor, the combination of a workpiece supporting cage adapted to be connected to said spindle, said cage including, a workpiece supporting bottom plate, a top plate connected to said spindle, spaced guide bars xed to said top and bottom plates, and a vertically movable plate positioned between and movable along said guide bars adapted to rest on the article to be cleaned.

. 20. Blast cleaning apparatus including in combination, a cabinet, means for projecting a stream of abrasive into said cab-inet to dene a blasting zone therein, an article supporting frame mounted for rotation in a substantially horizontal plane whereby the peripheral section thereof may be moved through said blasting zone, a plurality of asiaflss work supporting sleeves fixed to said frame in spaced relationship, a spindle rotatably supported by each of said sleeves, a work supporting device fixed to each of said spindles, a continuous cam track associated with said frame, driving means adapted to engage said cam track to rotate said frame by stop-and-go stages whereby the article supported on each of said spindles may reside in said blasting zone for a predetermined time interval, a sprocket fixed to each of said spindles, and a continuously driven drive chain positioned adjacent said blasting zone adapted to successively engage said sprockets to rotate said impeller when positioned adjacent said blasting zone.

21. Blast cleaning apparatus including in cornbination, a cabinet, means for projecting a stream of abrasive into said cabinet to deiine a blasting zone therein, an article supporting frame mounted for rotation in a substantially horizontal plane whereby the peripheral section thereof may be moved through said blasting zone, a plurality of work supporting sleeves fixed to said frame in spaced relationship, a spindle rotatably supported by each of said sleeves, a work supporting device fixed to each of said spindles, a continuous cam track associated with said frame, and driving means adapted to engage said cam track to rotate said frame by stop-and-go stages whereby the article supported on each of said spindles may reside in said blasting zone for a predetermined time interval, said means including a continuously driven drive chain, a vertically extending shaft, a pawl xed to said shaft, an abutment element carried by said chain adapted to engage said pawl to rotate said shaft through a predetermined angle during the travel of said chain, and a cam arm i'ixed to said shaft positioned to engage said cam track to rotate said frame through a predetermined angle upon rotation of said shaft.

ROY W. GUITE. 

